Insulin resistance is a well described feature of lean essential hypertensive patients. It has been reported to improve after therapy with the converting enzyme inhibitor captopril, which blocks the production of angiotensin II in addition to other effects such as potentiation of bradykinin levels. This study proposes to use the euglycemic insulin clamp technique to assess the role of angiotensin II in both the carbohydrate as well as the lipid abnormalities associated with the insulin resistance of essential hypertension.